Thermal printers are widely known and generally comprises a printing means comprising a thermally activatable printhead for printing onto an image receiving tape. Typically, the image receiving tape has an upper layer for receiving an image and a removable liner layer or backing layer secured to the upper layer by a layer of adhesive, such that after an image has been printed the liner layer or backing layer can be removed and the image receiving tape can be stuck down in the form of a label. Such thermal printers include cutters for cutting off a length of image receiving tape after the image has been printed. Such thermal printers operate with a consumable in the form of image receiving tape, or any other image receiving substrate such as heat shrink tube, magnetic, iron-on labels, plastic strips, etc. The term “consumable” is used herein to denote any appropriate form of providing image receiving tape. A number of forms of consumables are known in the art, including cassettes which comprise a housing in which is located a supply of image receiving tape. Cassettes are generally usable once only, such that once the image receiving tape has been consumed, the cassette (including the housing) is thrown away.
Another type of consumable is a holder, which comprises a spool around which image receiving tape is wound. The spool may or may not be driven, and generally comprises a plastic component.
Another type of consumable is a roll of tape without a permanent holder, for example wound on a paper core. These are termed “supplies”.
In thermal printers, an image is generally generated by activation of a thermal printhead against an ink ribbon cassette, such that ink from the ink ribbon is transferred onto the image receiving tape at a print zone. So-called direct thermal tapes are also available, in which an image is created directly onto the direct thermal tape without the interposition of an ink ribbon cassette.
The following documents are mentioned by way of general background. U.S. Pat. No. 5,494,365 discloses a tape spool with a tape identification member which can be optically read, to identify the nature of the tape. EP 1104701 relates to a cassette which selectively activates mechanical plunger switches in a thermal printer depending on the size and type of tape in the cassette. In EP 1104701, thermal transfer ribbon and image receiving tape are housed in the same cassette, so the compatibility issue does not arise.
None of these prior art documents address the problem of determining whether or not a particular thermal transfer ribbon and image receiving tape are compatible in a flexible and extensible way.
European Application No. 96114988.7 relates to a system where cassettes housing an image receiving tape and cassettes housing thermal transfer ribbon have protrusions which mate or not depending on whether the particular combination of cassettes (thermal transfer ribbon and image receiving tape) is compatible or not. Moreover, a cassette holding a direct thermal tape (which does not need an ink ribbon cassette with it) has a protrusion which prevents the insertion of an ink ribbon cassette at the same time.
This system requires the use of cassettes which can mechanically cooperate when in the printer, which is restrictive in terms of the printer layout. Also, the number of combinations which can be dealt with is necessarily limited because of the mechanical nature of the cooperating protrusions.